275 research outputs found
Electrical Characterization of Submicrometer Silicon Devices by Cross-Sectional Contact Mode Atomic Force Microscopy
Two contact mode atomic force microscopic (AFM) techniques under ambient conditions are presented for the electrical evaluation of cross sectioned silicon devices. In the first technique, a conductive AFM tip is used as a voltage probe to determine the local potential distribution on the cross section of a silicon device under operation. The electrical potential is measured simultaneously with the surface topography with nanometer resolution and mV accuracy, offering an easy way of correlating topographic and electrical features. A second method, nanometer spreading resistance profiling (nano-SRP), performs localized spreading resistance measurements to determine the spatial distribution of charge carriers in silicon structures. The conversion of the resistance profiles into charge carrier profiles as well as the applied correction factors are discussed in more detail. Both methods are used to map electrical characteristics of state-of-the-art silicon structures
A dynamic 3-D cardiac surface model from MR images
Cardiac 3D + time segmentation and motion estimation are recognized as difficult prerequisite tasks for any quan-titative analysis of cardiac images. Some recent algorithms aim to consider a temporal constraint to increase the ac-curacy of results. To improve the temporal consistency, prior knowledge about cardiac dynamics can be used. In this paper, we propose to build a new Statistical Dynamic Model (SDM) of the heart by learning through a popula-tion of healthy individuals. This SDM is composed by a set of semi-landmarks which describe the heart surfaces. For each of them, a mean trajectory and variability around it are derived. The SDM provides a reasonable constraint for a temporally regularized segmentation and motion track-ing algorithm. 1
High precision micro-scale Hall Effect characterization method using in-line micro four-point probes
Controlling lasing around Exceptional Points in Coupled Nanolasers
Coupled nanolasers are of growing interest for on-chip optical computation
and data transmission, which requires an understanding of how lasers interact
to form complex systems. The non-Hermitian interaction between two coupled
resonators, when excited selectively, can lead to parity-time symmetry, the
formation of exceptional points, and subsequently spectral control and
increased sensitivity. These investigations have been limited to pump energies
close to the lasing threshold, and large or narrow-line lasers. Here, by
programmable optical excitation we study two coupled nanolasers significantly
above threshold, where mode instability plays an important role. We map the
mode evolution around two exceptional points, and observe lasing gaps due to
reversed pump dependence which compare well with nonlinear theory. Finally, the
coupling can be exploited to control the lasing threshold and wavelength, and
for frequency switching around the lasing gap. Controlled and integrated
nanolasers constitutes a promising platform for future highly sensitive and
programmable on-chip laser sources.Comment: 8 pages, 4 figure
Myocardial Extracellular Volume Estimation by CMR Predicts Functional Recovery Following Acute MI
Objectives: In the setting of reperfused acute myocardial infarction (AMI), the authors sought to compare prediction of contractile recovery by infarct extracellular volume (ECV), as measured by T1-mapping cardiac magnetic resonance (CMR), with late gadolinium enhancement (LGE) transmural extent. Background: The transmural extent of myocardial infarction as assessed by LGE CMR is a strong predictor of functional recovery, but accuracy of the technique may be reduced in AMI. ECV mapping by CMR can provide a continuous measure associated with the severity of tissue damage within infarcted myocardium. Methods: Thirty-nine patients underwent acute (day 2) and convalescent (3 months) CMR scans following AMI. Cine imaging, tissue tagging, T2-weighted imaging, modified Look-Locker inversion T1 mapping natively and 15 min postâgadolinium-contrast administration, and LGE imaging were performed. The ability of acute infarct ECV and acute transmural extent of LGE to predict convalescent wall motion, ejection fraction (EF), and strain were compared per-segment and per-patient. Results: Per-segment, acute ECV and LGE transmural extent were associated with convalescent wall motion score (p < 0.01; p < 0.01, respectively). ECV had higher accuracy than LGE extent to predict improved wall motion (area under receiver-operating characteristics curve 0.77 vs. 0.66; p = 0.02). Infarct ECV â€0.5 had sensitivity 81% and specificity 65% for prediction of improvement in segmental function; LGE transmural extent â€0.5 had sensitivity 61% and specificity 71%. Per-patient, ECV and LGE correlated with convalescent wall motion score (r = 0.45; p < 0.01; r = 0.41; p = 0.02, respectively) and convalescent EF (p < 0.01; p = 0.04). ECV and LGE extent were not significantly correlated (r = 0.34; p = 0.07). In multivariable linear regression analysis, acute infarct ECV was independently associated with convalescent infarct strain and EF (p = 0.03; p = 0.04), whereas LGE was not (p = 0.29; p = 0.24). Conclusions: Acute infarct ECV in reperfused AMI can complement LGE assessment as an additional predictor of regional and global LV functional recovery that is independent of transmural extent of infarction
Multi-modality image simulation with the Virtual Imaging Platform: Illustration on cardiac echography and MRI
International audienceMedical image simulation is useful for biological modeling, image analysis, and designing new imaging devices but it is not widely available due to the complexity of simulators, the scarcity of object models, and the heaviness of the associated computations. This paper presents the Virtual Imaging Platform, an openly-accessible web platform for multi-modality image simulation. The integration of simulators and models is described and exemplified on simulated cardiac MRIs and ultrasonic images
Wafer-Scale, Sub-5 nm Junction Formation by Monolayer Doping and Conventional Spike Annealing
We report the formation of sub-5 nm ultrashallow junctions in 4 inch Si
wafers enabled by the molecular monolayer doping of phosphorous and boron atoms
and the use of conventional spike annealing. The junctions are characterized by
secondary ion mass spectrometry and non-contact sheet resistance measurements.
It is found that the majority (~70%) of the incorporated dopants are
electrically active, therefore, enabling a low sheet resistance for a given
dopant areal dose. The wafer-scale uniformity is investigated and found to be
limited by the temperature homogeneity of the spike anneal tool used in the
experiments. Notably, minimal junction leakage currents (<1 uA/cm2) are
observed which highlights the quality of the junctions formed by this process.
The results clearly demonstrate the versatility and potency of the monolayer
doping approach for enabling controlled, molecular-scale ultrashallow junction
formation without introducing defects in the semiconductor.Comment: 21 pages, 5 figure
Wages in high-tech start-ups - do academic spin-offs pay a wage premium?
Due to their origin from universities, academic spinâoffs operate at the forefront of the
technological development. Therefore, spinâoffs exhibit a skillâbiased labour demand, i.e. spinâoffs
have a high demand for employees with cutting edge knowledge and technical skills. In order to accommodate
this demand, spinâoffs may have to pay a relative wage premium compared to other
highâtech startâups. However, neither a comprehensive theoretical assessment nor the empirical
literature on wages in startâups unambiguously predicts the existence and the direction of wage differentials
between spinâoffs and nonâspinâoffs. This paper addresses this research gap and examines
empirically whether or not spinâoffs pay their employees a wage premium. Using a unique linked
employerâemployee data set of German highâtech startâups, we estimate Mincerâtype wage regressions
applying the HausmanâTaylor panel estimator. Our results show that spinâoffs do not pay a
wage premium in general. However, a notable exception from this general result is that spinâoffs that
commercialise new scientific results or methods provide higher wages to employees with linkages to
the university sector â either as university graduates or as student workers
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